In competitive swimming, the pacing of a swimmer is an important factor in improving competitiveness. Measurements of stroke information, such as the time required for one stroke in each of the swimmer's stroke (referred to hereinafter as the “stroke time”), the length advanced in one stroke (referred to hereinafter as the “stroke length”), etc., are thus demanded.
As a technique of measuring such stroke information, Japanese Unexamined Patent Publication (Tokukai) No. 2000-42161 (Reference 1) describes a technique with which an operator, while viewing the movement of a measured subject (for example, a competitive swimmer), presses a switch at each predetermined phase of a motion that is repeated by the measured subject to compute the period, etc., of the periodic motion.
Also, Japanese Unexamined Patent Publication (Tokukai) No. Hei-11-159173 (Reference 2) describes a technique of measuring stroke information by taking images of a swimming swimmer and capturing the movement of a hand of the swimmer by motion capture.